Riky
$MSFT
Performance isnt the only type of issue they can run in, massive pop-ins and second long frequent stutters would be among the problems they'd be facing due to low memory available. Those would not be acceptable for a release, unlike mere slowdowns to 20-15 fps.
I don't think the Devs have given that sort of detail of the problem have they? Since the game is running single player ok the resolution of the split screen makes the most sense to me personally, but it's all guesswork.